The current study was carried out at the Experimental Farm of Sakha Agricultural Research Station, Kafr El-Sheikh Governorate during 2016/2017 and 2017/2018 seasons for investigating the efficacy of Chrysoperla carnea (Stephens) larvae release against Cassida vittataVill. and Scrobipalpa ocellatella Boyd.larvae in sugar beet fields, at the same time in conserving arthropod predators (true spiders “Araneae", C. carnea, Coccinellidae, Anthocoridae and Formicidae), in comparison with conventional insecticides (Tac 48% EC, Diracomel 90% SP and Shalinger-Super 24% SC). The results indicated that the conventional insecticides induced reduction in the mean number of S. ocellatella larval population with 91.00, 86.00 and 89.03%, respectively in 2016/2017 season, and 92.00, 90.00 and 92.13%, respectively in 2017/2018 season. While in case of C. vittata the chemical insecticide treatments induced reduction in the mean number of larval population with 91.00, 93.40 and 94.00%, respectively in 2016/2017 season as well as 92.40, 94.10 and 94.33%, respectively in 2017/2018 season. Also, the mean of reductions in the surveyed and associated arthropod predators as a result of using conventional insecticides against S. ocellatella larvae were 96.71, 96.55, and 96.55%, respectively in 2016/2017 season as well as 95.30, 94.00 and 92.00%, respectively in 2017/2018 season. While in case of using chemical insecticides against C. vittata larvae, the reductions in the mean population of the surveyed and associated arthropod predators in sugar beet fields were 97.40, 96.30 and 95.00%, respectively in 2016/2017 season as well as 96.00, 94.00 and 93.30%, respectively in 2017/2018 season. While in the treatment of release the predatory insect,
C. carnea larvae against S. ocellatella larvae induced reduction in the mean number of the larval population by 57.13 and 43.40% in 2016/2017 and 2017/2018 seasons, respectively. While in case of C. vittata larvae, the reduction in the mean number of larval population recorded 49.00 and 45.13% in 2016/2017 and 2017/2018 seasons, respectively. Also, the surveyed and associated arthropod predator populations increased by 25.13 and 70.00% in 2016/2017 and 2017/2018 seasons, respectively. While the increasing in C. carnea populations were 22.00 and 44.13% in 2016/2017 and 2017/2018 seasons, respectively as a result of release the predatory insect, C. carnea for controlling both of S. ocellatella and C. vittata, respectively. Finally, these results show the important role of releasing C. carnea larvae as a biocontrol agent for controlling C. vittata and S. ocellatella larvae, at the same time in enhancing arthropod predator populations in comparison with conventional insecticides.